Evolution Flashcards
What is natural selection?
Organisms within a species show variation, i.e. they have varied characteristics due to differences in the genes.
All organisms compete for food, shelter from predators and mates.
Organisms that happen to have the characteristics that enable them to survive in their environment are more likely to breed successfully.
Thus passing on the genes that allowed them to survive (among other genes) to future generations
Why was Darwin’s theory only gradually accepted at his time? (4)
1) It went against contemporary beliefs that God created all the plants and animals.
2) He couldn’t produce sufficient evidence to convince many scientists.
3) Darwin could not explain why there was variety in organisms or how inheritance worked.
4) Scientists did not know about genes and genetics until about 50 years later.
What was Jean-Baptiste Lamarck’s theory of evolution?
Why is Darwin’s theory superior?
Lamarck’s theory was called ‘the inheritence of acquired caharacteristics’. Lamark’s theory stated that changes that happend during an organisms lifetime would be passed onto the next generation. For example if twop parents were to build up their muscles in the gym, Lamarck’s theory would predict that this characteristic would be passed onto the offspring.
In the vast majority of cases, this inheritance cannot occur, because external things hardly ever affect genetic information.
How can we understand and represent the relationships between organisms?
Biologists study the similarities and differences between organisms in order to classify them, the system used is called the natural classification system.
What is a mutation and how can this affect the process of natural selection?
In what situation may a mutation be particularly important?
A mutation is when a gene randomly and accidentally changes and becomes a new form of the gene. If the gene controls a characteristic which makes the organism better adapted to the environment, then it will be passed on to the offspring.
If the environment changes.
Why might there be various theories for one thing? What must be done in order to support or refute a theory?
Scientists may produce different hypotheses to explain similar observations.
These hypotheses must be investigated in order to support or refute a theory.
Give an example of when a mutated gene helped certain individuals within a species to survive during a period of environmental change.
When the rabbit disease myxomatosis killed most of the rabbits in the UK, a few rabbits had a mutated gene which gave them immunity. The rabbits with the mutated gene survived to breed.
What is the easiest system of classification to understand?
What are the largest groups called and what are the three main largest groups?
One which starts with large groups and splits these up gradually into smaller ones.
Kingdoms
The main kingdoms are:
The plant kingdom
The animal kingdom
The kingdoms which contain the microorganisms
What is the smallest group in the classification system?
What is special about members of the same species?
Species
They are very similar and can breed together to produce fertile offspring.
What are evolutionary trees?
Evolutionary trees are models that can be drawn to show the relationships between different groups of organisms.
What do ecological relationships tell us?
They tell us how species have evolved together in an environment.
